Apple is widely expected to introduce at least one new iPhone on September 10, if not two. The first will be a slightly improved variant of the iPhone 5, while the second will be a brand-new lower-cost model with a plastic shell. Each iPhone produced by Apple since 2007 has been a bona fide hit, but sales have begun to level off a bit in the face of stiff competition. What can Apple add to its iPhone in order to reignite the excitement that has historically driven sales into the tens of millions of units per quarter?

This week saw significant momentum gather behind the idea of a gold- or champagne-colored iPhone. Though the idea was initially ridiculed, it gained merit after a handful of leaks were followed by several confirmations published in The Wall Street Journal, The New York Times, and Reuters. The gold color will be available for the iPhone 5S, but not the iPhone 5C. The leaks suggest that the gold color is easy to anodize onto aluminum and could be a popular third option for the high-end iPhone.

The iPhone 5C, on the other hand, will sport a polycarbonate case that's available in a variety of colors. It will cost slightly less than the Phone 5S to produce, but by how much only Apple knows. The exact colors to be offered have not yet been leaked.

If there's one feature the iPhone has lacked, it is color -- the phone has been available in only black or white since its introduction. Adding a choice of colors is a welcome idea, but it by no means guarantees success for the next-gen iPhone.

The other big feature expected in the iPhone 5S is a fingerprint reader. Apple picked up Authentec, maker of fingerprint scanners, in early 2012. Such a scanner could be used for security purposes to unlock the device or to power mobile payments. Other than that, it's not clear what the feature could be used for.

One significant bit of technology that remains absent from the iPhone is near-field communications (NFC). NFC is a short-range radio tech that can be used for mobile payments, easy device pairing, and so on. The iPhone is one of the few leading smartphones that lacks NFC. Adding it to the iPhone 5S and 5C would be a welcome addition to the device, but again, nothing new as far as the industry is concerned.

Then there's wireless charging. Apple has so far shunned the idea of adding wireless charging features to the iPhone. Given that there are three specs still vying to become the default standard in wireless charging, it makes sense that Apple has held off. Without knowing which spec will eventually prevail, it would be fruitless for Apple to add the tech to the iPhone at this point.

These are all minor hardware features, though. Even if Apple adds all of them, the iPhone 5S will look nearly identical to the iPhone 5. That means it won't have a lot of visual pizazz to entice buyers. Further, many of these features and functions (NFC and wireless charging, for example) are already available on competing devices. It's not like Apple will be setting any technological precedents if it throws them in.

We also have a pretty good idea what Apple is bringing to the table with iOS 7. The operating system will arrive with a complete visual overhaul. Though the underlying functionality of the operating system will be much the same, all the icons, fonts, and colors have been changed. There are new features all over the place, such as the control drawer that slides up from the bottom, iTunes Radio for streaming music, improvements to Siri and Safari, and better lock-screen notifications and multitasking powers.

So are new colors, a few minor hardware tweaks, and a revised operating system enough to re-stoke interest in Apple's iPhone? Maybe -- or maybe not.

What do you think? What features do you want to see? What should Apple do to reignite the iPhone fire?